The invention relates to a measuring arrangement for rotationally symmetrical workpieces with longitudinal guides running in an axial direction of the workpiece and on which a measuring slide is movable, which carries at least one measuring head measuring the workpiece with a sensing pin in radial and/or axial direction, in which system the measuring head is movable transversely to the longitudinal guides on the measuring slide and in which the sensing pin is coupled over a spring element to the measuring head in such a way that it is movable at least in the radial direction with respect to the workpiece out of a basic position, in which on the spring part there is fastened at least one measurement value indicator, with which the position change of the sensing pin is detectable.
Measuring arrangements of this type are known. In them the workpieces are held either rigidly by a clamping prism or they are turnably borne between tail stocks with adjustable tail spindles.
These arrangements have the substantial disadvantage that on a change of the measuring assignment, under in part considerable manual expenditure, another sensing pin or measuring head must be mounted. Thereby a measuring of a workpiece with respect to several measuring magnitudes becomes very complicated and time-consuming.
The problem of the invention, therefore, is to specify a measuring apparatus with which a rapid change of different measuring sensors is possible, which are optimally suited for different measuring assignments.
There the change between the individual measuring sensors is to be rapid and possible without high assembling expenditure; furthermore it is to be simple to operate and economical.
The problem is solved according to the invention by the means that the sensing pin is arranged in a measuring pin carrier with at least two sensing pins, that the sensing pin carrier is arranged to turn about an axis perpendicular to the workpiece axis and in a plane that contains the workpiece axis, and that the sensing pin carrier is stoppable in each case in a rotary position allocated to the individual sensing pins.
The invention has the advantage that one measuring head is suited for several measuring assignments, so that a cost-intensive stocking of the most diverse measuring heads is eliminated. By the formation according to the invention of such a measuring head, in the case of another measuring assignment no other measuring head has to be mounted on the measuring apparatus, but it suffices to turn the sensing pin so that a suitable sensing pin is brought into the measuring position. As the sensing pin carrier is stoppable in individual rotary positions allocated to sensing pins, a high user-friendliness is achieved, since a time-consuming adjustment of the rotary position is eliminated such as would arise in an electrical position apparatus of the type often used.
In order to further improve the flexibility of the measuring arrangement it is advantageous to connect the sensing pin carrier changeably with the measuring head.
If there the sensing pin carrier is fastened with a clamping device to a rotary body which is turnably borne in the measuring head, then it is hereby avoided that in the changing of the sensing pin carrier the high-precision, play-free bearings required for its turning must be solved. The fastening of the sensing pin carrier to the rotary body must in this context be regarded as less critical.
The clamping arrangement with which the sensing pin carrier is fastened to the rotary body can be, for example, a clamping screw or a clamping lever. It is also thinkable, however, to provide on the rotary body a motor with a spindle which connects the sensing pin carrier over a thread with the rotary body. On the other hand, also an electromagnet or permanent magnet or a pneumatic suction device can be integrated into the rotary body, with which the connection is brought about between sensing pin carrier and rotary body.
In all these clamping arrangements it is favorable if the rotary body has a bearing, especially a three-point bearing, which clearly determines the position of the fastened sensing pin carrier to the rotary body. In a preferred embodiment this three-point bearing is formed by three cylindrical body pairs on the rotary body and three spherical cups corresponding with this on the sensing pin carrier. In order here to exactly define the angular position, the sensing pin carrier has an identifying pin which engages into a corresponding bore on the rotary body.
In order to make it possible to change the established rotary position of the sensing pin carrier without great expenditure of time, it is favorable if the stopping device fixing the rotary position is detachable. the stopping device fixing the rotary position is detachable.
In a preferred embodiment the stopping device has for this purpose a swingable stop lever, on which a groove formed by two cylindrical bodies, parallel to the axis of rotation of the sensing pin carrier is present, which corresponds to a ball cup on the turnable part, i.e. the sensing pin carrier or the rotary body, in which system the rotary part has further ball caps on the circumference allocated to individual sensing pins. In order to compensate for the tilting moment applied in this manner to the axis of the sensing pin carrier or of the rotary body, the stopping device can have at least two components arranged substantially opposite one another with respect to the sensing pin carrier or the rotary body.
In the preferred form of execution the stopping device has further lever without groove, which lies diametrically opposite the stop lever essentially and is in engagement with another ball cup, which lies essentially diametrically opposite the first ball cup. The radial forces thus applied to the turnable part cancel each other out, so that no resulting moment on the axis of rotation arises.
Since the sensing pin is to be springily borne with respect to the workpiece, in a preferred embodiment the spring element provided for this is a parallel leaf spring pair, which is fastened at its one end to the measuring head and which carriers on its free end elastically to the measuring head a receiving body on which the sensing pin carrier is turnably borne.
This leaf spring pair enables the sensing pin to be deflected springily only in one direction. In the event that the sensing pin is to be springily deflected in another direction, then the bearing of said leaf spring pair is to be provided in an intermediate member which can spring in the further deflection direction over a second leaf spring pair. Over a third leaf spring pair there can also occur a cardan suspension of the sensing pin.
The springy bearing of the receiving body makes it possible to achieve the springing of the sensing pins simply, since it is not necessary for each sensing pin to be separately springily borne.
A deflection of the sensing pin on the workpiece brings about a magnitude to be measured. In order to detect this simply, it is advantageous if the measuring element has at least one inductive path recorder which connects the spring element and the measuring head in the direction of the spring path.
In the above-described bearing with several leaf spring pairs, there is to be provided a separate path recorder correspondingly for each springing direction.
Besides an inductive path recorder it is also possible in the scope of the invention to use incremental measuring systems or to provide the leaf springs with extension-measuring springs and with these to determine the deflection of the sensing pin.
In order to make it possible largely to automate the measurement of a workpiece, it is advantageous if the sensing pin carrier is turnable by a motor. In order to achieve an exact turning, the sensing pin carrier and the motor can be joined with an angle coder on the sensing pin carrier and a tacho-generator on the motor in a regulating circuit.
On the one hand it is possible, to be sure, to fasten the motor directly to the shaft of the sensing pin carrier or of the rotary body, but thereby the inert mass of the spring part is strongly increased. It is advantageous, accordingly, if the motor presents on its offdrive shaft a wheel which, over a turning rim coaxially joined torsionally fast with the sensing pin carrier, brings about the rotary movement of the sensing pin carrier. Since here a turning speed and rotary angle reduction can take place, it is possible to use a more economical motor.
In a preferred embodiment the motor is rigidly fastened to the measuring head and the rotary rim of the sensing pin carrier is brought into active connection with the wheel on the motor by deflection of the springly borne receiving body in which the sensing pin carrier is borne. The deflection of the receiving body can occur especially simply by a setting device fastened to the measuring head, in which case there is yielded the constructive free space to fasten the setting device at any arbitrary place in the measuring head when it deflects the receiving body over a rocker arm borne turnably on the measuring head.
Further features and advantages of the invention are yielded from the following description of the drawing. In this: